class Phone:
    __is_5G_enable=False
    def __check_5G(self):
        if self.__is_5G_enable:
            print("5G is enabled")
        else:
            print("5G is not enabled, use 4G instead")
    def call_by_5G(self):
        self.__check_5G()
        print("Calling by 5G")
class Phone2(Phone):
    def call_by_6G(self):
        print("Calling by 6G")


# p1=Phone()
# p1.__is_5G_enable=True
# p1.call_by_5G()

p2=Phone2()
p2.__is_5G_enable=True
p2.call_by_5G()
p2.call_by_6G()